Method and apparatus for transmitting control information in wireless communication system

ABSTRACT

The present invention relates to a wireless communication system, particularly, a method in which a terminal transmits control information in a CA-based wireless communication system and an apparatus for the method, the method comprising: configuring a first cell and a second cell having different subframe configurations, wherein the second cell has any one of UL-DL configuration #0 to #6; receiving a DC) format including a DAI field, for the second cell; and transmitting HARQ-ACK information relating to the downlink DCI format. For HARQ-ACK timing, in cases where a reference UL-DL configuration applied to the second cell is any one of UL-DL configurations #1 to #6, the DAI field is used in a process of transmitting the HARQ-ACK information. For HARQ-ACK timing, in cases where a reference UL-DL configuration applied to the second cell is #0, the DAI field is not used in a process of transmitting the HARQ-ACK information.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National Stage filing under 35 U.S.C. 371 ofInternational Application No. PCT/KR2013/000308, filed on Jan. 15, 2013,which claims the benefit of earlier filing date and right of priority toKorean Application No. 10-2013-0004625, filed on Jan. 15, 2013, and alsoclaims the benefit of U.S. Provisional Application Serial Nos.61/586,827, filed on Jan. 15, 2012, 61/591,275, filed on Jan. 27, 2012,61/596,206, filed on Feb. 7, 2012, 61/678,594, filed on Aug. 1, 2012,61/693,339, filed on Aug. 27, 2012, 61/721,510, filed on Nov. 2, 2012and 61/722,136, filed on Nov. 3, 2012, the contents of which are allincorporated by reference herein in their entirety.

TECHNICAL FIELD

The present invention relates to a wireless communication system and,more particularly, to a method and apparatus for transmitting controlinformation in a carrier aggregation (CA)-based wireless communicationsystem.

BACKGROUND ART

Wireless communication systems have been widely deployed to providevarious types of communication services such as voice or data services.In general, a wireless communication system is a multiple access systemcapable of supporting communication with multiple users by sharingavailable system resources (bandwidth, transmit power, etc.). Multipleaccess systems include, for example, a code division multiple access(CDMA) system, frequency division multiple access (FDMA) system, timedivision multiple access (TDMA) system, orthogonal frequency divisionmultiple access (OFDMA) system, and single-carrier frequency divisionmultiple access (SC-FDMA) system.

DISCLOSURE Technical Problem

An object of the present invention devised to solve the problem lies ina method and apparatus for transmitting control information in a carrieraggregation (CA)-based wireless communication system. Another object ofthe present invention devised to solve the problem lies in a method andapparatus for efficiently transmitting and receiving acknowledgementinformation on a downlink/uplink (DL/UL) signal.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

Technical Solution

The object of the present invention can be achieved by providing amethod for transmitting control information by a user equipment (UE) ina carrier aggregation (CA)-based wireless communication system, themethod including configuring a first cell and a second cell havingdifferent subframe configurations, wherein the second cell is set to oneof uplink-downlink (UL-DL) configurations #0 to #6, receiving a DLdownlink control information (DCI) format including a downlinkassignment index (DAI) field, for the second cell, and transmittinghybrid automatic repeat request (HARQ)-acknowledgement (ACK) informationrelated to the DL DCI format, wherein, for HARQ-ACK timing, if areference UL-DL configuration applied to the second cell is one of UL-DLconfigurations #1 to #6, the DAI field is used in a procedure fortransmitting the HARQ-ACK information, wherein, for HARQ-ACK timing, ifa reference UL-DL configuration applied to the second cell is UL-DLconfiguration #0, the DAI field is not used in a procedure fortransmitting the HARQ-ACK information, and wherein subframeconfigurations according to the UL-DL configurations are given as shownin the following table.

UL-DL Subframe Number Configuration 0 1 2 3 4 5 6 7 8 9 0 D S U U U D SU U U 1 D S U U D D S U U D 2 D S U D D D S U D D 3 D S U U U D D D D D4 D S U U D D D D D D 5 D S U D D D D D D D 6 D S U U U D S U U D

In the above table, D denotes a DL subframe, U denotes a UL subframe,and S denotes a special subframe.

In another aspect of the present invention, provided herein is a userequipment (UE) used in a carrier aggregation (CA)-based wirelesscommunication system, the UE including a radio frequency (RF) unit, anda processor, wherein the processor configures a first cell and a secondcell having different subframe configurations, wherein the second cellis set to one of uplink-downlink (UL-DL) configurations #0 to #6,receives a DL downlink control information (DCI) format including adownlink assignment index (DAI) field, for the second cell, andtransmits hybrid automatic repeat request (HARQ)-acknowledgement (ACK)information related to the DL DCI format, wherein, for HARQ-ACK timing,if a reference UL-DL configuration applied to the second cell is one ofUL-DL configurations #1 to #6, the DAI field is used in a procedure fortransmitting the HARQ-ACK information, wherein, for HARQ-ACK timing, ifa reference UL-DL configuration applied to the second cell is UL-DLconfiguration #0, the DAI field is not used in a procedure fortransmitting the HARQ-ACK information, and wherein subframeconfigurations according to the UL-DL configurations are given as shownin the following table.

UL-DL Subframe Number Configuration 0 1 2 3 4 5 6 7 8 9 0 D S U U U D SU U U 1 D S U U D D S U U D 2 D S U D D D S U D D 3 D S U U U D D D D D4 D S U U D D D D D D 5 D S U D D D D D D D 6 D S U U U D S U U D

In the above table, D denotes a DL subframe, U denotes a UL subframe,and S denotes a special subframe.

The first cell may be set to UL-DL configuration #0, and the second cellmay be set to one of UL-DL configurations #1 to #6.

The first cell may be a primary cell (PCell), and the second cell may bea secondary cell (SCell).

The DL DCI format may further include a carrier indicator field (CIF).

The DL DCI format may include DCI format 1, 1A, 1B, 1C, 1D, 2, 2A, 2B,2C, or 2D.

The HARQ-ACK information may include at least one of acknowledgementinformation about a physical downlink shared channel (PDSCH) signalindicated by the DL DCI format, and acknowledgement information about aphysical downlink control channel (PDCCH) signal including the DL DCIformat and indicating semi-persistent scheduling (SPS) release.

In another aspect of the present invention, provided herein is a methodfor transmitting control information by a user equipment (UE) in acarrier aggregation (CA)-based wireless communication system, the methodincluding configuring a first cell and a second cell having differentsubframe configurations, wherein the second cell is set to one ofuplink-downlink (UL-DL) configurations #1 to #6, receiving a DL downlinkcontrol information (DCI) format including a downlink assignment index(DAI) field, for the second cell, and transmitting hybrid automaticrepeat request (HARQ)-acknowledgement (ACK) information related to theDL DCI format, wherein, for HARQ-ACK timing, if a reference UL-DLconfiguration applied to the second cell is UL-DL configuration #0, theDAI field is not used in a procedure for transmitting the HARQ-ACKinformation, and wherein subframe configurations according to the UL-DLconfigurations are given as shown in the following table.

UL-DL Subframe Number Configuration 0 1 2 3 4 5 6 7 8 9 0 D S U U U D SU U U 1 D S U U D D S U U D 2 D S U D D D S U D D 3 D S U U U D D D D D4 D S U U D D D D D D 5 D S U D D D D D D D 6 D S U U U D S U U D

In the above table, D denotes a DL subframe, U denotes a UL subframe,and S denotes a special subframe.

In another aspect of the present invention, provided herein is a userequipment (UE) used in a carrier aggregation (CA)-based wirelesscommunication system, the UE including a radio frequency (RF) unit, anda processor, wherein the processor configures a first cell and a secondcell having different subframe configurations, wherein the second cellis set to one of uplink-downlink (UL-DL) configurations #1 to #6,receives a DL downlink control information (DCI) format including adownlink assignment index (DAI) field, for the second cell, andtransmits hybrid automatic repeat request (HARQ)-acknowledgement (ACK)information related to the DL DCI format, wherein, for HARQ-ACK timing,if a reference UL-DL configuration applied to the second cell is UL-DLconfiguration #0, the DAI field is not used in a procedure fortransmitting the HARQ-ACK information, and wherein subframeconfigurations according to the UL-DL configurations are given as shownin the following table.

UL-DL Subframe Number Configuration 0 1 2 3 4 5 6 7 8 9 0 D S U U U D SU U U 1 D S U U D D S U U D 2 D S U D D D S U D D 3 D S U U U D D D D D4 D S U U D D D D D D 5 D S U D D D D D D D 6 D S U U U D S U U D

In the above table, D denotes a DL subframe, U denotes a UL subframe,and S denotes a special subframe.

The first cell may be set to UL-DL configuration #0.

The first cell may be a primary cell (PCell), and the second cell may bea secondary cell (SCell).

The DL DCI format may further include a carrier indicator field (CIF).

The DL DCI format may include DCI format 1, 1A, 1B, 1C, 1D, 2, 2A, 2B,2C, or 2D.

The HARQ-ACK information may include at least one of acknowledgementinformation about a physical downlink shared channel (PDSCH) signalindicated by the DL DCI format, and acknowledgement information about aphysical downlink control channel (PDCCH) signal including the DL DCIformat and indicating semi-persistent scheduling (SPS) release.

Advantageous Effects

According to the present invention, control information may beefficiently transmitted in a carrier aggregation (CA)-based wirelesscommunication system. In addition, acknowledgement information on adownlink/uplink (DL/UL) signal may be efficiently transmitted andreceived.

It will be appreciated by persons skilled in the art that that theeffects that could be achieved with the present invention are notlimited to what has been particularly described hereinabove and otheradvantages of the present invention will be more clearly understood fromthe following detailed description taken in conjunction with theaccompanying drawings.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, illustrate embodiments of the inventionand together with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates a carrier aggregation (CA)-based wirelesscommunication system;

FIG. 2 illustrates the structure of a radio frame;

FIG. 3 illustrates a resource grid of a downlink (DL) slot;

FIG. 4 illustrates the structure of a DL subframe;

FIG. 5 illustrates a scheduling method when a plurality of cells areconfigured;

FIG. 6 illustrates the structure of an uplink (UL) subframe;

FIG. 7 illustrates the structures of physical uplink control channel(PUCCH) formats 1a and 1b in a slot level;

FIG. 8 illustrates the structure of PUCCH format 3 in a slot level;

FIG. 9 illustrates a method for transmitting uplink control information(UCI) on a physical uplink shared channel (PUSCH);

FIGS. 10 and 11 illustrate UL acknowledgement (ACK)/negativeacknowledgement (NACK) timing of a time division duplex (TDD)-configuredcell;

FIGS. 12 to 15 illustrate UL grant/physical hybrid automatic repeatrequest (HARQ) indicator channel (PHICH) transmission timing of aTDD-configured cell;

FIG. 16 illustrates an ACK/NACK transmission procedure using a downlinkassignment index (DAI);

FIG. 17 illustrates the structure of half duplex (HD)-TDD CA;

FIG. 18 illustrates the structure of full duplex (FD)-TDD CA;

FIG. 19 illustrates a control information transmission procedureaccording to an embodiment of the present invention;

FIG. 20 illustrates a UL signal transmission procedure according to anembodiment of the present invention; and

FIG. 21 illustrates a base station (BS) and a user equipment (UE)applicable to an embodiment of the present invention.

BEST MODE

Techniques described herein may be used in a variety of wireless accesssystems such as Code Division Multiple Access (CDMA), Frequency DivisionMultiple Access (FDMA), Time Division Multiple Access (TDMA), OrthogonalFrequency Division Multiple Access (OFDMA), Single Carrier FrequencyDivision Multiple Access (SC-FDMA), etc. CDMA may be implemented as aradio technology such as Universal Terrestrial Radio Access (UTRA) orCDMA2000. TDMA may be implemented as a radio technology such as GlobalSystem for Mobile communications (GSM)/General Packet Radio Service(GPRS)/Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may beimplemented as a radio technology such as IEEE 802.11 (Wi-Fi), IEEE802.16 (WiMAX), IEEE 802.20, Evolved-UTRA (E-UTRA) etc. UTRA is a partof Universal Mobile Telecommunications System (UMTS). 3rd GenerationPartnership Project (3GPP) Long Term Evolution (LTE) is a part ofEvolved UMTS (E-UMTS) using E-UTRA. LTE-Advanced (LTE-A) is an evolutionof 3GPP LTE.

For clarity, the following description focuses on 3GPP LTE/LTE-A.However, technical features of the present invention are not limitedthereto. It should be noted that specific terms used herein are providedfor better understanding of the present invention, and the use of thesespecific terms may be changed to other formats within the technicalscope or spirit of the present invention.

In a wireless communication system, a user equipment (UE) receivesdownlink (DL) information from a base station (BS), and transmits uplink(UL) information to the BS. In LTE(-A), DL transmission is performedusing OFDMA, and UL transmission is performed using SC-FDMA.

The terms used in the specification will now be described.

-   -   HARQ-ACK (hybrid automatic repeat request acknowledgement): this        represents an acknowledgement response, i.e., an acknowledgement        (ACK)/negative acknowledgement (NACK)/discontinuous transmission        (DTX) response (simply, ACK/NACK (response), A/N (response)), to        downlink transmission (e.g. physical downlink shared channel        (PDSCH) or semi-persistent scheduling release physical downlink        control channel (SPS release PDCCH)). The ACK/NACK response        refers to ACK, NACK, DTX, or NACK/DTX. A HARQ-ACK regarding a        component carrier (CC) (or cell) or a HARQ-ACK of a CC refers to        an ACK/NACK response to downlink transmission related to (e.g.        scheduled for) the CC. A PDSCH can be replaced by a transport        block (TB) or a codeword.    -   PDSCH: this includes a PDSCH corresponding to a DL grant PDCCH,        and a semi-persistent scheduling (SPS) PDSCH.    -   SPS PDSCH: this is a PDSCH transmitted in DL using resources        semi-statically configured according to SPS. The SPS PDSCH has        no DL grant PDCCH corresponding thereto. The SPS PDSCH is used        interchangeably with a PDSCH w/o PDCCH.    -   SPS release PDCCH: this refers to a PDCCH indicating SPS        release. A UE feeds back ACK/NACK information about an SPS        release PDCCH.    -   DAI (downlink assignment index): this is included in downlink        control information (DCI) transmitted on a PDCCH. The DAI can        indicate an order value or counter value of a PDCCH. A value        indicated by a DAI field of a DL grant PDCCH is called a DL DAI        (V^(DL) _(DAI), simply V), and a value indicated by a DAI field        of a UL grant PDCCH is called a UL DAI (V^(UL) _(DAI), W^(UL)        _(DAT), simply W) for convenience.    -   PCC (primary component carrier) PDCCH: this indicates a PDCCH        that schedules a PCC. That is, the PCC PDCCH represents a PDCCH        corresponding to a PDSCH on the PCC. The PCC PDCCH is        transmitted only on the PCC on the assumption that cross-carrier        scheduling is not permitted for the PCC. The term PCC is used        interchangeably with PCell (primary cell).    -   SCC (secondary component carrier) PDCCH: this indicates a PDCCH        that schedules an SCC. That is, the SCC PDCCH represents a PDCCH        corresponding to a PDSCH on the SCC. The SCC PDCCH can be        transmitted on a CC (e.g. PCC) other than the SCC when        cross-carrier scheduling is permitted for the SCC. The SCC PDCCH        is transmitted only on the SCC when cross-carrier scheduling is        not permitted for the SCC. The term SCC is used interchangeably        with SCell (secondary cell).    -   Cross-carrier scheduling: this refers to an operation of        transmitting a PDCCH that schedules an SCC through a CC (e.g.        PCC) other than the SCC. All PDCCHs are scheduled/transmitted        only through a PCC when only the PCC and one SCC are present.    -   Non-cross-carrier scheduling: this refers to an operation of        scheduling/transmitting a PDCCH that schedules each CC through        the corresponding CC.

FIG. 1 illustrates a carrier aggregation (CA)-based wirelesscommunication system. Although an LTE system supports a single DL/ULfrequency block only, to use a wider frequency band, the LTE-A systememploys CA technology for aggregating a plurality of UL/DL frequencyblocks to obtain a wider UL/DL bandwidth. Each frequency block istransmitted using a component carrier (CC). The CC can be regarded as acarrier frequency (or center carrier, center frequency) for thefrequency block.

Referring to FIG. 1, a plurality of UL/DL CCs can be aggregated tosupport a wider UL/DL bandwidth. The CCs may be contiguous ornon-contiguous in the frequency domain. Bandwidths of the CCs may bedetermined independently. Asymmetrical CA in which the number of UL CCsis different from the number of DL CCs is also possible. For example,when there are two DL CCs and one UL CC, the DL CCs may correspond tothe UL CC at a ratio of 2:1. DL CC/UL CC links may be fixed orsemi-statically configured in the system. Although the system bandwidthis configured with N CCs, a frequency band usable by a specific UE maybe restricted to L (<N) CCs. Various parameters about CA may be setcell-specifically, UE-group-specifically, or UE-specifically. Controlinformation may be transmitted and received only in a specific CC. Thisspecific CC may be referred to as a primary CC (PCC) (or anchor CC) andother CCs may be referred to as secondary CCs (SCCs).

In LTE(-A), the concept of a cell is used to manage radio resources. Acell is defined as a combination of DL resources and UL resources, andthe UL resources are not mandatory. Accordingly, a cell may beconfigured with DL resources only or both DL resources and UL resources.When CA is supported, the linkage between carrier frequencies of DLresources (or DL CCs) and carrier frequencies of UL resources (or ULCCs) may be indicated by system information. A cell operating in primaryfrequency resources (or a PCC) may be referred to as a primary cell(PCell) and a cell operating in secondary frequency resources (or anSCC) may be referred to as a secondary cell (SCell). The PCell is usedin an initial connection establishment or connection re-establishmentprocedure of a UE. The PCell may refer to a cell indicated duringhandover. The SCell may be configured after a radio resource control(RRC) connection is established, and used to provide additional radioresources. The PCell and SCell may be collectively referred to asserving cells. Accordingly, only a single serving cell composed of aPCell exists for a UE in RRC_CONNECTED state, for which CA is not set orwhich does not support CA. On the other hand, a plurality of servingcells including a PCell and one or more SCells may be configured for aUE in RRC_CONNECTED state, for which CA is set.

Unless separately mentioned, the following description may be applied toeach of a plurality of aggregated CCs (or cells). In addition, a CC inthe following description may be replaced with a serving CC, servingcarrier, cell, serving cell, etc.

FIG. 2 illustrates the structure of a radio frame.

FIG. 2( a) illustrates the structure of a type-1 radio frame forfrequency division duplex (FDD). A radio frame includes a plurality of(e.g., 10) subframes, and each subframe includes a plurality of (e.g.,2) slots in the time domain. Each subframe may have a length of 1 ms andeach slot may have a length of 0.5 ms. A slot includes a plurality ofOFDM/SC-FDMA symbols in the time domain and includes a plurality ofresource blocks (RBs) in the frequency domain.

FIG. 2( b) illustrates the structure of a type-2 radio frame for timedivision duplex (TDD). The type-2 radio frame includes 2 half frames,and each half frame includes 5 subframes. One subframe includes 2 slots.

Table 1 shows uplink-downlink configurations (UL-DL Cfgs) of subframesin a radio frame in a TDD mode.

TABLE 1 Downlink- to-Uplink Uplink- Switch- downlink point Subframenumber configuration periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U U DS U U U 1 5 ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms  DS U U U D D D D D 4 10 ms  D S U U D D D D D D 5 10 ms  D S U D D D D DD D 6 5 ms D S U U U D S U U D

In Table 1, D denotes a DL subframe, U denotes a UL subframe, and Sdenotes a special subframe. The special subframe includes a downlinkpilot time slot (DwPTS), a guard period (GP), and an uplink pilot timeslot (UpPTS). The DwPTS is a time period reserved for downlinktransmission and the UpPTS is a time period reserved for uplinktransmission.

FIG. 3 illustrates a resource grid of a DL slot.

Referring to FIG. 3, a DL slot includes a plurality of OFDMA (or OFDM)symbols in the time domain. One DL slot may include 7(6) OFDMA symbols,and one resource block (RB) may include 12 subcarriers in the frequencydomain. Each element on the resource grid is referred to as a resourceelement (RE). One RB includes 12×7(6) REs. The number N^(RB) of RBsincluded in the DL slot depends on a downlink transmit bandwidth. Thestructure of a UL slot may be same as that of the DL slot except thatOFDMA symbols are replaced by SC-FDMA symbols.

FIG. 4 illustrates the structure of a DL subframe.

Referring to FIG. 4, up to 3(4) OFDMA symbols located in a front portionof a first slot within a subframe correspond to a control region towhich a control channel is allocated. The remaining OFDMA symbolscorrespond to a data region to which a physical downlink shared chancel(PDSCH) is allocated. Examples of downlink control channels include aphysical control format indicator channel (PCFICH), a physical downlinkcontrol channel (PDCCH), a physical HARQ indicator channel (PHICH), etc.The PCFICH is transmitted at a first OFDM symbol of a subframe andcarries information regarding the number of OFDMA symbols used fortransmission of control channels within the subframe. The PHICH is aresponse to uplink transmission and carries a HARQ acknowledgement(ACK)/negative acknowledgement (NACK) signal.

A PDCCH may carry a transmission format and resource allocationinformation of a downlink shared channel (DL-SCH), a transmission formatand resource allocation information of an uplink shared channel(UL-SCH), paging information on a paging channel (PCH), systeminformation on the DL-SCH, resource allocation information of anupper-layer control message such as a random access response transmittedon the PDSCH, a set of Tx power control commands on individual UEswithin an arbitrary UE group, a Tx power control command, information onactivation of a voice over IP (VoIP), etc.

Downlink control information (DCI) is transmitted on a PDCCH. DCIformats 0/4 (hereinafter referred to as UL DCI formats) is defined forUL scheduling (or UL grant), and DCI format 1/1A/1B/1C/1D/2/2A/2B/2C(hereinafter referred to as DL DCI format) is defined for DL scheduling.The DCI format selectively includes information such as hopping flag, RBallocation information, modulation coding scheme (MCS), redundancyversion (RV), new data indicator (NDI), transmit power control (TPC),demodulation reference signal (DMRS) cyclic shift, depending on its use.

A plurality of PDCCHs may be transmitted within a control region. A UEmay monitor the PDCCHs in every subframe to check a PDCCH designated tothe UE. The PDCCH is transmitted on an aggregation of one or severalconsecutive control channel elements (CCEs). The CCE is a logicalallocation unit used to provide the PDCCH with a coding rate based on astate of a radio channel. The CCE corresponds to a plurality of resourceelement groups (REGs). A PDCCH coding rate may be controlled accordingto the number of CCEs (i.e., CCE aggregation level) used for PDCCHtransmission. The CCE includes a plurality of resource element groups(REGs). A format of the PDCCH and the number of PDCCH bits aredetermined according to the number of CCEs. A BS determines a PDCCHformat according to DCI to be transmitted to the UE, and attaches acyclic redundancy check (CRC) to control information. The CRC is maskedwith an identifier (e.g., radio network temporary identifier (RNTI))according to an owner or usage of the PDCCH. If the PDCCH is for aspecific UE, an identifier (e.g., cell-RNTI (C-RNTI)) of the UE may bemasked to the CRC. Alternatively, if the PDCCH is for a paging message,a paging identifier (e.g., paging-RNTI (P-RNTI)) may be masked to theCRC. If the PDCCH is for system information (more specifically, a systeminformation block (SIB)), a system information RNTI (SI-RNTI) may bemasked to the CRC. When the PDCCH is for a random access response, arandom access-RNTI (RA-RNTI) may be masked to the CRC.

Then, a description is now given of scheduling when a plurality of CCs(or cells) are configured. If a plurality of CCs are configured,cross-carrier scheduling scheme and non-cross-carrier scheduling (orself scheduling) scheme may be used. The non-cross-carrier scheduling(or self scheduling) scheme is the same as the legacy LTE schedulingscheme.

If cross-carrier scheduling is configured, a DL grant PDCCH may betransmitted in DL CC#0, and a corresponding PDSCH may be transmitted inDL CC#2. Likewise, a UL grant PDCCH may be transmitted in DL CC#0, and acorresponding physical uplink shared channel (PUSCH) may be transmittedin UL CC#4. For cross-carrier scheduling, a carrier indicator field(CIF) is used. Whether a CIF is present in a PDCCH may be determinedthrough higher layer signaling (e.g., RRC signaling) using semi-staticand UE-specific (or UE-group-specific) schemes.

Scheduling according to whether a CIF is set may be defined as describedbelow.

-   -   CIF disabled: A PDCCH in a DL CC allocates PDSCH resources in        the same DL CC or allocates PUSCH resources in one linked UL CC.    -   CIF enabled: A PDCCH in a DL CC may allocate PDSCH or PUSCH        resources in a specific DL/UL CC among a plurality of aggregated        DL/UL CCs, using a CIF.

When a CIF is present, a BS may allocate one or more PDCCH monitoring DLCCs (hereinafter referred to as monitoring CCs (MCCs)) to a UE. The UEmay detect/decode a PDCCH in the MCCs. That is, if the BS schedules aPDSCH/PUSCH to the UE, a PDCCH is transmitted only in the MCCs. The MCCsmay be set using UE-specific, UE-group-specific, or cell-specificscheme. The MCCs include a PCC.

FIG. 5 illustrates cross-carrier scheduling. Although DL scheduling isillustrated in FIG. 5, the illustrated scheme is equally applied to ULscheduling.

Referring to FIG. 5, 3 DL CCs may be configured for a UE, and DL CC Amay be set as a PDCCH monitoring DL CC (i.e., MCC). If a CIF isdisabled, each DL CC may transmit a PDCCH for scheduling its PDSCHwithout the CIF according to the LTE PDCCH rules. On the other hand, ifa CIF is enabled, DL CC A (i.e., MCC) may transmit not only a PDCCH forscheduling its PDSCH but also PDCCHs for scheduling PDSCHs of other CCs,using the CIF. In this example, DL CC B/C transmits no PDCCH.

FIG. 6 illustrates the structure of a UL subframe.

Referring to FIG. 6, a UL subframe includes a plurality of (e.g. 2)slots. A slot may include different numbers of SC-FDMA symbols accordingto a CP length. The UL subframe is divided into a control region anddata region in the frequency domain. The data region is allocated with aPUSCH and used to carry a data signal such as audio data. The controlregion is allocated a physical uplink control channel (PUCCH) and usedto carry uplink control information (UCI). The PUCCH includes an RB pairlocated at both ends of the data region in the frequency domain andhopped in a slot boundary.

The PUCCH can be used to transmit the following control information.

-   -   SR (scheduling request): This is information used to request        UL-SCH resources and is transmitted using on-off keying (OOK)        scheme.    -   HARQ-ACK: This is a response signal to a downlink signal (e.g.,        PDSCH, SPS release PDCCH). For example, 1-bit ACK/NACK is        transmitted as a response to one DL codeword and 2-bit ACK/NACK        is transmitted as a response to two DL codewords.    -   CSI (Channel Status Information): This is feedback information        on a DL channel and includes channel quality information (CQI),        rank indicator (RI), precoding matrix indicator (PMI), precoding        type indicator (PTI), etc.

Table 2 shows the mapping relationship between a PUCCH format and UCI inLTE(-A).

TABLE 2 PUCCH Format Uplink Control Information (UCI) Format 1 SR(scheduling request) (unmodulated waveform) Format 1a 1-bitHARQ-ACK/NACK (with/without SR) Format 1b 2-bit HARQ-ACK/NACK(with/without SR) Format 2 CSI (20 coded bits) Format 2 CSI and 1-bit or2-bit HARQ-ACK/NACK (20 bits) (for extended CP only) Format 2a CSI and1-bit HARQ-ACK/NACK (20 + 1 coded bits) Format 2b CSI and 2-bitHARQ-ACK/NACK (20 + 2 coded bits) Format 3 Up to 24 bits ofHARQ-ACK/NACK + SR (LTE-A)

FIG. 7 illustrates the structures of PUCCH formats 1a and 1b in a slotlevel. In PUCCH formats 1a and 1b, the same control information isrepeated on a slot basis in a subframe. Each UE transmits an ACK/NACKsignal in different resources configured by a different cyclic shift(CS) (frequency-domain code) and a different orthogonal cover code (OCC)(time-domain spreading code) of a computer-generated constant amplitudezero auto correlation (CG-CAZAC) sequence. An OCC includes a Walsh/DFTorthogonal code. If the number of CSs is 6 and the number of OCs is 3,ACK/NACK signals of 18 UEs may be multiplexed into the same physicalresource block (PRB).

FIG. 8 illustrates the structure of PUCCH format 3 in a slot level.PUCCH format 3 is used to transmit a plurality of pieces of ACK/NACKinformation, and information such as an SR may be transmitted together.

Referring to FIG. 8, one symbol sequence is transmitted over thefrequency domain, and OCC-based time-domain spreading is applied to thesymbol sequence. Control signals of a plurality of UEs may bemultiplexed into the same RB using OCCs. Specifically, 5 SC-FDMA symbols(i.e. a UCI data part) are generated from one symbol sequence {d1, d2, .. . } using a length-5 OCC. Here, the symbol sequence {d1, d2, . . . }may be a modulation symbol sequence or a codeword bit sequence. Thesymbol sequence {d1, d2, . . . } may be generated by performing jointcoding (e.g., Reed-Muller coding, tail-biting convolutional coding,etc.), block-spreading, and SC-FDMA modulation on a plurality of piecesof ACK/NACK information.

FIG. 9 illustrates a method for transmitting UCI on a PUSCH. A subframewhich requires UCI transmission has PUSCH assignment, UCI may betransmitted on a PUSCH (PUSCH piggyback). Specifically, an ACK/NACK ispunctured into a part of resources of SC-FDMA to which UL-SCH data ismapped. The ACK/NACK is located adjacent to a reference signal (RS). TheUCI may be scheduled to be transmitted on the PUSCH without UL-SCH data.

A description is now given of an ACK/NACK transmission procedure in aTDD-configured CC (or cell) and a signal transmission timing thereofwith reference to FIGS. 10 to 15.

FIGS. 10 and 11 illustrate ACK/NACK (A/N) timing (or HARQ timing).

Referring to FIG. 10, a UE may receive one or more PDSCH signals in M DLsubframes (SFs) (S502_0 to S502_M−1) (M≧1). Each PDSCH signal mayinclude one or more (e.g., 2) transport blocks (TBs) according to atransmission mode. Although not shown in FIG. 10, a PDCCH signalindicating SPS release may also be received in steps S502_0 to S502_M−1.When a PDSCH signal and/or SPS release PDCCH signal are present in the MDL subframes, the UE transmits an ACK/NACK in one UL subframecorresponding to the M DL subframes through a procedure for ACK/NACKtransmission (e.g. ACK/NACK (payload) generation, ACK/NACK resourceallocation, etc.) (S504). The ACK/NACK includes acknowledgementinformation on the PDSCH signal and/or SPS release PDCCH signal of stepsS502_0 to S502_M−1.

Although the ACK/NACK is basically transmitted on a PUCCH, if there isPUSCH transmission at ACK/NACK transmission timing, the ACK/NACK istransmitted on a PUSCH. If a plurality of CCs are configured for the UE,the PUCCH is transmitted only in a PCC, and the PUSCH is transmitted ina scheduled CC. A variety of PUCCH formats shown in Table 2 may be usedfor ACK/NACK transmission. Furthermore, a variety of schemes such asACK/NACK bundling, ACK/NACK channel selection, etc. may be used toreduce the number of ACK/NACK bits to be transmitted in the PUCCHformat.

As described above, in TDD, an ACK/NACK of DL signals received in M DLsubframes is transmitted in one UL subframe (i.e., M DL SF(s):1 UL SF),and the relationship therebetween is given by a downlink association setindex (DASI).

Table 3 shows a DASI (K: {k₀, k₁, . . . , k_(M-1)}) defined for LTE(-A).Table 3 shows the interval between a UL subframe for transmitting anACK/NACK, and a DL subframe associated with the UL subframe.Specifically, if a PDCCH indicating PDSCH transmission and/or SPSrelease is present in subframe n-k (kεK), a UE transmits an ACK/NACK insubframe n.

TABLE 3 TDD UL-DL Subframe n Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 —4 — — 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7,4, 6 — — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4,7 — — — — — — 5 — — 13, 12, 9, 8, 7, 5, 4, 11, 6 — — — — — — — 6 — — 7 75 — — 7 7 —

FIG. 11 illustrates A/N timing applied to a CC having UL-DL Cfg #1. InFIG. 11, SF#0 to SF#9, and SF#10 to SF#19 correspond to radio frames.The numeral in a box denotes a DL subframe associated with a ULsubframe. For example, an ACK/NACK of a PDSCH of SF#5 is transmitted inSF#5+7 (=SF#12), and an ACK/NACK of a PDSCH of SF#6 is transmitted inSF#6+6 (=SF#12). That is, an ACK/NACK of SF#5/SF#6 is transmitted inSF#12. Likewise, an ACK/NACK of a PDSCH of SF#14 is transmitted inSF#14+4 (=SF#18).

FIGS. 12 and 13 illustrate UL grant (UG)/PHICH-PUSCH timing. A PUSCH maybe transmitted in response to a PDCCH (UL grant) and/or PHICH (NACK).

Referring to FIG. 12, a UE may receive a PDCCH (UL grant) and/or PHICH(NACK) (S702). Here, the NACK corresponds to an ACK/NACK response toprevious PUSCH transmission. In this case, the UE may initially transmitor retransmit one or more TBs on a PUSCH after k subframes through aprocedure for PUSCH transmission (e.g., TB coding, TB-CW swapping, PUSCHresource allocation, etc.) (S704). This example assumes a normal HARQoperation in which a PUSCH is transmitted once. In this case, a PHICH/ULgrant corresponding to PUSCH transmission is present in the samesubframe. However, in subframe bundling in which a PUSCH is transmitteda plurality of times in a plurality of subframes, a UL grant/PHICHcorresponding to PUSCH transmission may be present in differentsubframes.

Table 4 shows an uplink association index (UAI) (k) for PUSCHtransmission in LTE(-A). Table 4 shows the interval between a DLsubframe in which a PHICH/UL grant is detected, and a UL subframeassociated with the DL subframe. Specifically, if a PHICH/UL grant isdetected in subframe n, a UE may transmit a PUSCH in subframe n+k.

TABLE 4 TDD UL-DL subframe number n Configuration 0 1 2 3 4 5 6 7 8 9 04 6 4 6 1 6 4 6 4 2 4 4 3 4 4 4 4 4 4 5 4 6 7 7 7 7 5

FIG. 13 illustrates PUSCH transmission timing when UL-DL Cfg #1 is set.In FIG. 13, SF#0 to SF#9, and SF#10 to SF#19 correspond to radio frames.The numeral in a box denotes a UL subframe associated with a DLsubframe. For example, a PUSCH for a PHICH/UL grant of SF#6 istransmitted in SF#6+6 (=SF#12), and a PUSCH for a PHICH/UL grant ofSF#14 is transmitted in SF#14+4 (=SF#18).

FIGS. 14 and 15 illustrate PUSCH-UL grant (UG)/PHICH timing. A PHICH isused to transmit a DL ACK/NACK. Here, the DL ACK/NACK is a response toUL data (e.g., PUSCH) and refers to an ACK/NACK transmitted in downlink.

Referring to FIG. 14, a UE transmits a PUSCH signal to a BS (S902).Here, the PUSCH signal is used to transmit one or more (e.g., 2) TBsaccording to a transmission mode. As a response to PUSCH transmission,the BS may transmit an ACK/NACK to the UE on a PHICH after k subframesthrough a procedure for ACK/NACK transmission (e.g., ACK/NACKgeneration, ACK/NACK resource allocation, etc.) (S904). The ACK/NACKincludes acknowledgement information on the PUSCH signal of step S902.If the response to PUSCH transmission is a NACK, the BS may transmit aUL grant PDCCH for retransmitting the PUSCH, to the UE after k subframes(S904). This example assumes a normal HARQ operation in which a PUSCH istransmitted once. In this case, a UL grant/PHICH corresponding to PUSCHtransmission may be transmitted in the same subframe. However, insubframe bundling, a UL grant/PHICH corresponding to PUSCH transmissionmay be transmitted in different subframes.

Table 5 shows PHICH timing defined for TDD. For PUSCH transmission ofsubframe #n, a UE determines corresponding PHICH resources in subframe#(n+k_(PHICH)).

TABLE 5 TDD UL-DL UL subframe index n Configuration 0 1 2 3 4 5 6 7 8 90 4 7 6 4 7 6 1 4 6 4 6 2 6 6 3 6 6 6 4 6 6 5 6 6 4 6 6 4 7

FIG. 15 illustrates UL grant/PHICH transmission timing when UL-DL Cfg #1is set. In FIG. 15, SF#0 to SF#9, and SF#10 to SF#19 correspond to radioframes. The numeral in a box denotes a DL subframe associated with a ULsubframe. For example, a PHICH/UL grant corresponding to a PUSCH of SF#2is transmitted in SF#2+4 (=SF#6), and a UL grant/PHICH corresponding toa PUSCH of SF#8 is transmitted in SF#8+6 (=SF#14).

In a TDD-configured CC (or cell), when a UE transmits an ACK/NACK signalto a BS, if the UE has missed a part of PDCCH(s) transmitted from the BSin a period of a plurality of subframes, the UE does not even know thata PDSCH corresponding to the missed PDCCH was transmitted to the UE andthus an error may occur in generating ACK/NACK.

To solve this problem, a DL grant PDCCH/SPS release PDCCH for a TDD CCincludes a DAI field (i.e., DL DAI field). The value of DL DAI fielddesignates an cumulative value (i.e., count) of PDCCH(s) correspondingto PDSCH(s) and PDCCH(s) indicating downlink SPS release to a currentsubframe within DL subframe(s) n-k (kεK). For example, if 3 DL subframescorrespond to one UL subframe, PDSCHs transmitted in a period of 3 DLsubframes are sequentially indexed (i.e., sequentially counted) and theindex (or count) is delivered on a PDCCH for scheduling the PDSCHs. TheUE may determine whether a previous PDCCH is appropriately received, bychecking DAI information of the PDCCH.

FIG. 16 illustrates an ACK/NACK transmission procedure using a DL DAI.This example assumes a TDD system configured by 3 DL subframes:1 ULsubframe. It is assumed for convenience that a UE transmits ACK/NACKusing PUSCH resources. In LTE, when ACK/NACK is transmitted on a PUSCH,1-bit or 2-bit bundled ACK/NACK is transmitted.

Referring to FIG. 16, if the second PDCCH is missed as shown in Example1, since a DL DAI value of the third PDCCH is different from a currentlydetected number of PDCCHs, the UE may know that the second PDCCH ismissed. In this case, the UE may process an ACK/NACK response to thesecond PDCCH as a NACK (or NACK/DTX). On the other hand, if the lastPDCCH is missed as shown in Example 2, since the last detected DAI valueof a PDCCH is equal to a currently detected number of PDCCHs, the UE maynot recognize that the last PDCCH is missed (i.e., DTX). Accordingly,the UE recognizes that only two PDCCHs are scheduled for a DL subframeperiod. In this case, the UE bundles ACK/NACK corresponding to first twoPDCCHs and thus an error occurs in an ACK/NACK feedback procedure. Tosolve this problem, a UL grant PDCCH also includes a DAI field (i.e., ULDAI field). The UL DAI field is a 2-bit field and includes informationabout the number of scheduled PDCCHs.

Table 6 shows values (V^(DL) _(DAI), V^(UL) _(DAI)) indicated by a DAIfield in a DCI format. V^(DL) _(DAI) denotes a DL DAI value, and V^(UL)_(DAI) denotes a UL DAI value. V^(DL) _(DAI) denotes the value of DAIfield in DCI format 1/1A/1B/1D/2/2A/2B/2C/2D for UL-DL Cfgs #0 to #6.V^(UL) _(DAI) denotes the value of DAI field in DCI format 0/4 (i) ifone CC (or cell) having UL-DL Cfgs #1 to #6 is configured, or (ii) if aUE is configured not to use PUCCH format 3.

TABLE 6 Number of subframes with PDSCH DAI transmission and with PDCCHMSB, LSB V_(DAI) ^(UL) or V_(DAI) ^(DL) indicating DL SPS release 0, 0 11 or 5 or 9 0, 1 2 2 or 6 1, 0 3 3 or 7 1, 1 4 0 or 4 or 8

MSB: Most significant bit. LSB: Least significant bit.

Table 7 shows a value (W^(UL) _(DAT)) indicated by a DAI field in DCIformat 0/4. W^(UL) _(DAI) denotes the value of DAI field in DCI format0/4 (i) if a plurality of CCs (or cells) having UL-DL Cfgs #1 to #6 areconfigured, or (ii) if one CC (or cell) having UL-DL Cfgs #1 to #6 isconfigured and a UE is configured to use PUCCH format 3.

TABLE 7 DAI MSB, LSB W_(DAI) ^(UL) 0, 0 1 0, 1 2 1, 0 3 1, 1 4

MSB: Most significant bit. LSB: Least significant bit.

For convenience, unless otherwise mentioned, DL DAI is referred to as V,and UL DAI is referred to as W.

DAI is used in various ways in an ACK/NACK transmission procedure. Forexample, a DAI may be used for DTX detection as illustrated in FIG. 16,or used in an ACK/NACK payload generating procedure (e.g., determinationof the size of ACK/NACK payload and the location of ACK/NACK informationin the ACK/NACK payload) or ACK/NACK resource allocation procedure.

Initially, a description is now given of DTX detection using a DAI.Referring back to FIG. 16, when V^(UL) _(DAI)≠(U_(DAI)+N_(SPS)−1)mod 4+1it is assumed that at least one DL assignment is missed (i.e., DTXoccurs), and a UE generates a NACK of all codewords according to abundling procedure. U_(DAI) denotes a total number of DL grant PDCCHsand SPS release PDCCHs detected in subframe n-k (kεK) (see Table 3).N_(SPS) denotes the number of SPS PDSCHs and is 0 or 1.

Then, a description is now given of ACK/NACK payload generation using aDAI. It is assumed for convenience that PUCCH format 3 is configured.ACK/NACK payloads for PUCCH format 3 are configured per cell, andarranged in the order of cell indices. Specifically, HARQ-ACK feedbackbits for a c-th serving cell (or DL CC) are given as o_(c,0) ^(ACK)o_(c,1) ^(ACK), . . . , o_(c,O) _(c) _(ACK) ⁻¹ ^(ACK) (c≧0). O^(ACK)_(C) denotes the number of bits (i.e., size) of HARQ-ACK payload of thec-th serving cell. Regarding the c-th serving cell, if a transmissionmode for supporting transmission of a single TB is configured or ifspace bundling is applied, it may be given as O^(ACK) _(c)=B^(DL) _(c).

On the other hand, regarding the c-th serving cell, if a transmissionmode for supporting transmission of a plurality of (e.g., 2) TBs isconfigured and space bundling is not applied, it may be given as O^(ACK)_(c)=2B^(DL) _(c). If the HARQ-ACK feedback bits are transmitted on aPUCCH or if the HARQ-ACK feedback bits are transmitted on a PUSCH butthere is no W corresponding to the PUSCH (e.g., SPS-based PUSCH), it isgiven as B^(DL) _(c)=M. M denotes the number of elements in set Kdefined in Table 3. If the TDD UL-DL Cfg is #1, #2, #3, #4, or #6 and ifthe HARQ-ACK feedback bits are transmitted on a PUSCH, it is given asB^(DL) _(c)=W^(UL) _(DAI). W^(UL) _(DAI) denotes a value indicated by aUL DAI field in a UL grant PDCCH (Table 7), and is simply referred to asW. If the TDD UL-DL Cfg is #5, it is given as B_(c) ^(DL)=W_(DAI)^(UL)+4┌(U−W_(DAI) ^(UL))/4└. Here, U denotes a maximum value among Ucs,and Uc denotes a total number of PDSCH(s) received and PDCCHs indicating(downlink) SPS release in subframe n-k in the c-th serving cell.Subframe n is a subframe for transmitting the HARQ-ACK feedback bits. ┌┐ denotes a ceiling function.

Regarding the c-th serving cell, if a transmission mode for supportingtransmission of a single TB is configured or if space bundling isapplied, the location of each ACK/NACK in HARQ-ACK payload of theserving cell is given as o_(c,DAI(k)-1) ^(ACK). DAI(k) denotes a DL DAIvalue of a PDCCH detected in DL subframe n-k. On the other hand,regarding the c-th serving cell, if a transmission mode for supportingtransmission of a plurality of (e.g., 2) TBs is configured and spacebundling is not applied, the location of each ACK/NACK in HARQ-ACKpayload of the serving cell is given as o_(c,2DAI(k)-2) ^(ACK)o_(c,2DAI(k)-1) ^(ACK). o_(c,2DAI(k)-2) ^(ACK) denotes HARQ-ACK forcodeword 0, and o_(c,2DAI(k)-1) ^(ACK) denotes HARQ-ACK for codeword 1.Codeword 0 and codeword 1 may respectively correspond to TB0 and TB1, orTB1 and TB0 according to swapping. If PUCCH format 3 is transmitted in asubframe configured for SR transmission, PUCCH format 3 transmitsACK/NACK bits and a 1-bit SR together.

A beyond LTE-A system considers aggregation of a plurality of CCs havingdifferent subframe configurations. For example, a plurality of CCshaving different subframe configurations includes aggregation of aplurality of CCs having different UL-DL Cfgs (referred to as differentTDD CA for convenience). Although different TDD CA is assumed in thefollowing description, aggregation of a plurality of CCs havingdifferent subframe configurations is not limited thereto. In differentTDD CA, A/N timing (see FIGS. 10 and 11) set for a PCC and SCC may bedifferent according to UL-DL Cfgs of the corresponding CCs. Accordingly,UL SF timing for transmitting A/N may be set differently for the PCC andSCC with respect to the same DL SF timing, and a DL SF group for whichA/N feedback is transmitted may be set differently for the PCC and theSCC with respect to the same UL SF timing. Furthermore, link directions(i.e. DL/UL) of the PCC and SCC may be set differently with respect tothe same SF timing.

In addition, the beyond LTE-A system considers to support cross-CCscheduling even when a plurality of CCs having different subframeconfigurations are aggregated. In this case, UL grant/PHICH timing (seeFIGS. 12 to 15) configured for an MCC and SCC may be different. Forexample, a DL SF for transmitting a UL grant/PHICH may be configureddifferently for the MCC and SCC with respect to the same UL SF.Furthermore, a UL SF group for which a UL grant or PHICH feedback istransmitted may be configured differently for the MCC and SCC withrespect to the same DL SF. In this case, link directions of the MCC andSCC may be configured differently with respect to the same SF timing.For example, specific SF timing may be configured as a DL SF fortransmitting a UL grant/PHICH in the SCC, and configured as a UL SF inthe MCC.

When SF timing at which link directions of the PCC and SCC are different(hereinafter referred to as a collided SF) is present due to differentsubframe configurations (e.g., different TDD CA configurations), only aCC from the PCC and SCC, which has a specific link direction or has thesame link direction as that of a specific CC (e.g. PCC), may be utilizedat the SF timing due to the hardware configuration of the UE or anotherreason/purpose. For convenience, this scheme is referred to as halfduplex (HD)-TDD CA. For example, when SF collision occurs becausespecific SF timing is configured as a DL SF in the PCC and configured asa UL SF in the SCC, only the PCC having a DL direction (i.e. DL SF setfor the PCC) may be utilized and the SCC having a UL direction (i.e. ULSF set for the SCC) may not be utilized at the SF timing (or viceversa).

In this case, to transmit A/N feedback about a DL signal transmitted inDL SFs of all CCs, through the PCC, a scheme for applying A/N timing(set for a specific UL-DL Cfg) differently per CC or commonly to all CCsmay be considered. Here, the specific UL-DL Cfg (hereinafter referred toas a reference configuration (Ref-Cfg)) may be the same as a UL-DL Cfgconfigured for the PCC or SCC or determined as another UL-DL Cfg.Although the Ref-Cfg is illustrated in view of A/N timing in FIGS. 17and 18, the Ref-Cfg may also be defined in view of UL grant/PHICHtiming. In this case, a Ref-Cfg for A/N timing (hereinafter referred toas an A/N timing Ref-Cfg) and a Ref-Cfg for UL grant/PHICH timing(hereinafter referred to as a UL grant/PHICH timing Ref-Cfg) are givenindependently. Simply, the A/N timing Ref-Cfg may be referred to as aDL-Ref UL/DL configuration, and the UL grant/PHICH timing Ref-Cfg may bereferred to as a UL-Ref UL/DL configuration.

In HD-TDD CA, the number of DL SFs for which A/N feedback is transmitted(hereinafter referred to as A/N-DL SFs) at one UL SF timing may be setdifferently for a PCC and SCC. In other words, if the number of DL SFscorresponding to one UL SF (referred to as A/N-DL SFs for convenience)is defined as M, the value M may be set differently or independently forCCs with respect to one PCC UL SF (the value M for each CC: Mc). If anA/N timing Ref-Cfg of a specific XCC (PCC or SCC) is not the same as aPCC UL-DL Cfg (i.e., PCC-Cfg), an A/N-DL SF index of the XCC set at PCCUL SF timing may be different from an A/N-DL SF index achieved when A/Ntiming of an original PCC-Cfg is applied. Particularly, if PUCCHresources linked to CCE resources of a PDCCH for scheduling DL data arereferred to as an implicit PUCCH, the implicit PUCCH may not be defined(in a PCC UL SF for transmitting A/N) for a specific XCC DL SF (a PDCCHfor scheduling DL data to be transmitted therein) even in cross-CCscheduling.

FIG. 17 illustrates the structure of HD-TDD CA. In FIG. 17, shaded partsX denote a CC (link direction), use of which is prohibited in a collidedSF, and a dotted arrow denotes a DL SF corresponding to a PCC UL SF towhich an implicit PUCCH is not linked.

A scheme for allowing simultaneous DL/UL transmission and reception in acollided SF in which link directions of a PCC and SCC are different maybe considered. For convenience, this scheme is referred to as fullduplex (FD)-TDD CA. In this case, A/N timing set for a specific (A/Ntiming) Ref-Cfg may also be applied differently to each CC or commonlyto all CCs in order to transmit A/N feedback for DL SFs of all CCs inone PCC UL SF. The (A/N timing) Ref-Cfg may be the same as a PCC-Cfg orSCC-Cfg or given as another UL-DL Cfg. In FD-TDD CA, a value M may beset differently or independently for CCs with respect to one PCC UL SF,and implicit PUCCH resources may not be defined in (a PCC UL SFcorresponding to) an XCC DL SF even in cross-carrier scheduling. FIG. 18illustrates the structure of FD-TDD CA, and a dotted arrow denotes a DLSF corresponding to a PCC UL SF to which implicit PUCCH resources arenot linked.

Embodiment Control Information Signaling in Aggregation of CCs HavingDifferent Subframe Configurations

Referring to Tables 6 and 7, a DAI is used for CCs having UL-DL Cfgs #1to #6, and not used for a CC having UL-DL Cfg #0 (UL-DL Cfg #0 CC). InUL-DL Cfg #0 in which the number of UL SFs is greater than the number ofDL SFs, unlike the other UL-DL Cfgs, for a UL grant DCI format, a ULindex indicating a UL SF to be scheduled is signaled (instead of a ULDAI). That is, the UL grant DCI format selectively includes a DAI fieldand UL index field according to the UL-DL Cfg, and the DAI field and ULindex field are defined as having the same size (e.g., 2 bits). Here,the UL index may be used to determine the index of a subframe used forPUSCH transmission. Furthermore, in a DL grant DCI format for the UL-DLCfg #0 CC, it is defined that (a DL DAI field is present but) a DL DAIis not signaled. That is, although a DL field is present, a DL DAI field(value) is not used. The UL grant DCI format includes DCI format 0/4,and the DL grant DCI format includes DCI format1/1A/1B/1D/2/2A/2B/2C/2D. The UL index is signaled in UL-DL Cfg #0 toperform UL scheduling/HARQ on a large number of UL SFs using a smallnumber of DL SFs. In addition, since the number of UL SFs is greaterthan the number of DL SFs in UL-DL Cfg #0, each of the DL SFs can belinked to different UL SF (for A/N transmission) and thus DL DAIsignaling may be omitted.

In CA of a plurality of CCs having different subframe configurations(e.g., CA of a plurality of CCs having different UL-DL Cfgs), if a CChaving UL-DL Cfg #0 is present, a (HARQ timing) Ref-Cfg of the CC havingUL-DL Cfg #0 may be configured as a UL-DL Cfg of another CC, or a thirdUL-DL Cfg (in this case, UL index signaling may not be necessary). Inthis regard, in view of A/N transmission, a plurality of DL SFs of theCC having UL-DL Cfg #0 may be linked to one UL SF of a PCC. Accordingly,if UL-DL Cfg #N (N: integer other than 0 (e.g., 1 to 6)) is configuredas a Ref-Cfg for the CC having UL-DL Cfg #0, providing of DL/UL DAIsignaling to a DL/UL grant DCI format for scheduling DL/UL data on theCC having UL-DL Cfg #0 may be more efficient for A/N transmission.

Initially, the present invention proposes a DAI signaling scheme using aDCI format for scheduling a CC having UL-DL Cfg #0 (i.e., CC operatingwith UL-DL Cfg #0) in TDD (hereinafter referred to as a UL-DL Cfg #0scheduling DCI format), and an A/N transmission method thereof. As onescheme, a case in which DL DAI signaling is activated in a UL-DL Cfg #0scheduling DL grant DCI format may include (i) a case in which a UE iscapable of performing CA, (ii) a case in which a plurality of CCs areassigned for a UE, (iii) a case in which a plurality of CCs havingdifferent UL-DL Cfgs are assigned for a UE, (iv) a case in which PUCCHformat 3 is configured for A/N transmission, and a combination thereof.This is because, when PUCCH format 3 is configured, PUCCH formatdetermination, A/N transmission on a PUSCH, simultaneous transmission ofCSI or SR and A/N, etc. is performed depending on a DL DAI.

As another scheme, only when PUCCH format 3 is configured for A/Ntransmission (i) in CA of one or more CCs having UL-DL Cfg #0, (ii) by aUE capable of performing CA (of CCs having a UL-DL Cfg (#0)), and/or(iii) in CA of one or more CCs (having a UL-DL Cfg (#0)), it may beassumed that a DL DAI of a DL grant PDCCH for scheduling a correspondingCC corresponds to a DL DAI initial value (e.g., 1) while DL DAIsignaling is not activated as in a conventional case. This is becausethe use of a TPC field in the DL grant PDCCH (e.g., PUCCH power controlor A/N resource indication) and determination of a PUCCH format for A/Ntransmission, an A/N payload configuration for A/N transmission on aPUSCH, simultaneous transmission of CSI or SR and A/N, etc. are alldetermined according to value of the DL DAI (or, whether value of the DLDAI corresponds to the DL DAI initial value). Accordingly, when a DLgrant PDCCH for scheduling an arbitrary CC is received, a UEcorresponding to the above condition may regard that the DL DAI initialvalue for the corresponding CC is received, and perform TPC fieldreference, PUCCH power control, A/N resource determination, A/N payloadconfiguration, simultaneous transmission of CSI or SR and A/N, etc.

Meanwhile, a case in which UL DAI signaling is activated in a UL-DL Cfg#0 scheduling UL grant DCI format may be restricted to CA of a pluralityof CCs having different UL-DL Cfgs (excluding a case in which UL indexsignaling is inevitable).

Furthermore, in CA of a plurality of CCs having different UL-DL Cfgs,whether a DCI format supports DL DAI, UL DAI signaling may be determinedaccording to TDD CA combination/structure, whether cross-carrierscheduling is configured, A/N timing Ref-Cfg, UL grant/PHICH timingRef-Cfg, etc.

The present invention now proposes a method of determining whether DL/ULDAI signaling is supported, and a method of configuring A/N payload tobe transmitted on a PUSCH (or PUCCH). The following description assumesfor convenience that one PCC (or MCC) and one SCC having different UL-DLCfgs are aggregated, and may be extended to a case in which a pluralityof CCs having different subframe configurations are aggregated.Furthermore, in the following description, a DL grant DCI formatincludes those of a PDCCH for scheduling DL data, and a PDCCH forcommanding SPS release. DL data (or DL signal) collectively refers to aPDCCH and PDSCH which require ACK/NACK feedback, and includes a PDCCHfor instructing SPS release. A DL SF may include not only a general DLSF but also a special SF. In addition, a DCI format for scheduling a CChaving UL-DL Cfg #0 (i.e., CC having or operating with UL-DL Cfg #0) isreferred to as a UL-DL Cfg #0 scheduling DCI format.

<DL DAI Signaling>

(1) Method D-1: No DL DAI Signaling is Provided Using a (UL-DL Cfg #0Scheduling) DL Grant DCI Format

The size of A/N payload of a CC operating with UL-DL Cfg #0 may alwaysbe determined as a maximum size irrespective of an A/N transmissionchannel (e.g., PUCCH or PUSCH) (and irrespective of the value of UL DAIor whether the UL DAI is present). Here, the maximum size may correspondto a total number of DL SFs of UL-DL Cfg #0 linked to one PCC UL SF inview of A/N transmission. The corresponding A/N payload of UL-DL Cfg #0may be ordered in the order of DL SFs instead of the order of DL DAIs.Meanwhile, this method may be applied only to a case in which the PCChas UL-DL Cfg #0 (i.e., case in which an A/N timing Ref-Cfg of the PCCis set to a PCC UL-DL Cfg). The Ref-Cfg of the PCC follows the UL-DL Cfgof the PCC. Furthermore, this method may be applied only to a CC whichoperates with UL-DL Cfg #0 and of which an A/N timing Ref-Cfg is set toUL-DL Cfg #0. In addition, this method may be applied to a CC of whichan A/N timing Ref-Cfg is set to UL-DL Cfg #0, irrespective of UL-DLCfgs. For example, if a CC has one of UL-DL Cfgs #0 to #6 (particularly,one of UL-DL Cfgs #1 to #6) and an A/N timing Ref-Cfg of the CC is setto UL-DL Cfg #0, no DAI signaling is provided using a DL grant DCIformat for the CC. In this case, the proposed A/N payload configurationand A/N ordering scheme may be equally applied.

(2) Method D-2: DL DAI Signaling is Provided Using a (UL-DL Cfg #0Scheduling) DL Grant DCI Format

This method may be applied only to a case in which an SCC has UL-DL Cfg#0 (i.e., case in which an A/N timing Ref-Cfg of an SCC is set to a PCCUL-DL Cfg). Furthermore, this method may be applied only to a CC whichoperates with UL-DL Cfg #0 (hereinafter referred to as a UL-DL Cfg #0CC) and of which an A/N timing Ref-Cfg is set to a UL-DL Cfg other thanUL-DL Cfg #0. In addition, this method may be applied to a CC of whichan A/N timing Ref-Cfg is set to a UL-DL Cfg other than UL-DL Cfg #0,irrespective of UL-DL Cfgs. For example, if a CC has one of UL-DL Cfgs#0 to #6 (particularly, UL-DL Cfg #0) and an A/N timing Ref-Cfg of theCC is set to one of UL-DL Cfgs #1 to #6, DAI signaling may be providedusing a DL grant DCI format of the CC.

Meanwhile, in a PCC having UL-DL Cfg #0, an A/N timing Ref-Cfg of eachCC may be determined as described below according to whethercross-carrier scheduling is configured. Here, cross-carrier schedulingmay refer to scheduling of DL data to be transmitted in an SCC, by aPCC.

-   -   Case #1: (PCC, SCC)=UL-DL Cfg (#0, #N); cross-carrier scheduling    -   A/N timing Ref-Cfg of PCC: UL-DL Cfg #0 (i.e., PCC UL-DL Cfg)    -   A/N timing Ref-Cfg of SCC: UL-DL Cfg #0 (i.e., PCC UL-DL Cfg)    -   Case #2: (PCC, SCC)=UL-DL Cfg (#0, #N); non-cross-carrier        scheduling    -   A/N timing Ref-Cfg of PCC: UL-DL Cfg #0 (i.e., PCC UL-DL Cfg)    -   A/N timing Ref-Cfg of SCC: UL-DL Cfg #N (i.e., SCC UL-DL Cfg)

Here, Case #1 may be generalized to a case in which both CC1 and CC2have an A/N timing Ref-Cfg set to UL-DL Cfg #0. Furthermore, Case #2 maybe generalized to a case in which CC1 and CC2 respectively have an A/Ntiming Ref-Cfg set to UL-DL Cfg #0 and an A/N timing Ref-Cfg set toUL-DL Cfg #N (N≧1). CC1 may be a PCC and CC2 may be an SCC. In thefollowing description, the PCC and SCC may be respectivelyinterchangeable with CC1 and CC2.

The present invention proposes the following schemes in Case #1 and Case#2. For convenience, activation/deactivation of DL DAI signaling isreferred to as DL DAI ON/OFF. Here, DL DAI ON indicates that the valueof a DL DAI field in a DCI format is usable in an A/N transmissionprocedure, and DL DAI OFF indicates that a DL DAI field is not includedin a DCI format, or a DL DAI field is present but the value of the DLDAI field is not usable in an A/N transmission procedure.

-   -   Sol-1: DL DAI OFF for PCC, DL DAI ON for SCC    -   A UE may operate by assuming/regarding that all DL grant PDCCHs        for scheduling a PCC and/or DL data correspond to the first DL        SF or a DL DAI initial value (e.g., 1). Alternatively, the A/N        payload (i.e., maximum size) and A/N ordering (i.e., DL SF        order) scheme of Method D-1 may be applied to a PCC and SCC        (irrespective of a transmission channel, e.g., PUCCH or PUSCH,        and irrespective of the value of UL DAI/whether the UL DAI is        present).    -   Sol-2: DL DAI OFF for both PCC and SCC    -   A UE may operate by assuming/regarding that all DL grant PDCCHs        for scheduling a PCC and SCC and/or DL data correspond to the        first DL SF or a DL DAI initial value (e.g., 1). Alternatively,        the A/N payload (i.e., maximum size) and A/N ordering (i.e., DL        SF order) scheme of Method D-1 may be applied to a PCC and SCC        (irrespective of a transmission channel, e.g., PUCCH or PUSCH,        and irrespective of the value of UL DAI/whether the UL DAI is        present).    -   Sol-3: DL DAI ON for both PCC and SCC    -   An operation may not be separately defined as in Sol-1 and        Sol-2. As a result, DL DAI signaling may always be activated        irrespective of an A/N timing Ref-Cfg (whether it corresponds to        UL-DL Cfg #0).

Meanwhile, the scheme may be applied to Case #1 and Case #2 (e.g., Sol-2or Sol-3 may be commonly applied to Case #1 and Case #2), or differentschemes may be applied to Case #1 and Case #2 (e.g., Sol-2 may beapplied to Case #1, and Sol-1 or Sol-3 may be applied to Case #2).

Alternatively, Sol-2 may be applied if every CC has an A/N timingRef-Cfg configured as UL-DL Cfg #0, and Sol-1 or Sol-3 may be applied ifthere is a CC having an A/N timing Ref-Cfg not configured as UL-DL Cfg#0. Otherwise, Sol-3 may be applied if every CC has an A/N timingRef-Cfg not configured as UL-DL Cfg #0, and Sol-1 or Sol-2 may beapplied if there is a CC having an A/N timing Ref-Cfg configured asUL-DL Cfg #0.

Meanwhile, the above-described schemes (e.g., Sol-1 to Sol-3) may beapplied only when “PUCCH format 1b with channel selection” is set forA/N transmission.

FIG. 19 illustrates a control information transmission procedureaccording to an embodiment of the present invention. This embodimentshows combination [Method D-1, Method D-2], and other combinations maybe performed similarly. For example, this embodiment may be performedsimilarly on combination [Method D-1/D-2, Case#1, Sol-2].

Referring to FIG. 19, a plurality of cells (e.g., cell#1 and cell#2)having different subframe configurations may be configured for a UE(S1702). Here, cell#2 may have one of UL-DL Cfgs #0 to #6 (particularly,one of UL-DL Cfgs #1 to #6). Although cell types are not restrictive,cell#1 may be a PCell and cell#2 may be a SCell. After that, the UE mayreceive a DL DCI format including a DAI field, for cell#2 (S1704). Sincecross-carrier scheduling is configured in Case#1, the DL DCI format mayfurther include a CIF field. The DL DCI format includes DCI format1/1A/1B/1C/1D/2/2A/2B/2C/2D. After that, the UE may transmit HARQ-ACKinformation related to the DL DCI format in uplink (S1706). Here, theHARQ-ACK information may include at least one of acknowledgementinformation about a PDSCH signal indicated by the DL DCI format, andacknowledgement information about an SPS release PDCCH signal includingthe DL DCI format.

According to the present invention, for HARQ-ACK timing, if a referenceUL-DL Cfg (Ref-Cfg) applied to cell#2 is not UL-DL Cfg #0 (Method D-2),a DAI field may be used in a procedure for transmitting HARQ-ACKinformation (e.g., DTX detection, HARQ-ACK payload generation, HARQ-ACKresource allocation, etc.) (Method D-2). On the other hand, for HARQ-ACKtiming, if a Ref-Cfg applied to cell#2 is UL-DL Cfg #0 (MethodD-1/Case#1), a DAI field is not used in a procedure for transmittingHARQ-ACK information (Sol-2). In this case, a HARQ-ACK payload size of acell operating with UL-DL Cfg #0 may always be determined as a maximumsize irrespective of a HARQ-ACK transmission channel (e.g., PUCCH orPUSCH) (and irrespective of the value of UL DAI/whether the UL DAI ispresent). Here, the maximum size may correspond to a total number of DLSFs of UL-DL Cfg #0 linked to one PCell UL SF in view of HARQ-ACKtransmission (see Table 3). The HARQ-ACK payload of the cell operatingwith UL-DL Cfg #0 may be ordered in the order of DL SFs instead of theorder of DL DAIs.

<UL DAI Signaling>

(1) Method U-1: No UL DAI Signaling is Provided Using a UL-DL Cfg #0Scheduling UL Grant DCI Format

According to this method, a UL index may be signaled instead of a UL DAIwith respect to the same field in a DCI format. Furthermore, the size ofA/N payload of each CC having UL-DL Cfg #0 when A/N is transmitted on aPUSCH of the CC may be determined as a maximum size. Here, the maximumsize may correspond to a total number of DL SFs of each CC linked to onePCC UL SF in view of A/N transmission (see Table 3). Specifically, A/Npayload of a CC for providing DL DAI signaling may be ordered in theorder of DL DAIs and A/N payload of a CC for not providing DL DAIsignaling may be ordered in the order of DL SFs, or A/N payload of allCCs may be ordered in the order of DL SFs.

Meanwhile, this method may be applied only to (i) a case in which an MCChas UL-DL Cfg #0 (a UL grant/PHICH timing Ref-Cfg of an MCC is set to anMCC UL-DL Cfg), (ii) a case in which an SCC has UL-DL Cfg #0 andnon-cross-carrier scheduling is configured, and (iii) a case in which anSCC has UL-DL Cfg #0 and cross-carrier scheduling and FD-TDD CA areconfigured (a UL grant/PHICH timing Ref-Cfg of an SCC is set to an SCCUL-DL Cfg). Furthermore, this method may be applied only to a CC whichoperates with UL-DL Cfg #0 (hereinafter referred to as a UL-DL Cfg #0CC) and of which a UL grant/PHICH timing Ref-Cfg is set to UL-DL Cfg #0.In addition, this method may be applied to a CC of which a ULgrant/PHICH timing Ref-Cfg is set to UL-DL Cfg #0, irrespective of UL-DLCfgs. For example, if a CC has one of UL-DL Cfgs #0 to #6 (particularly,one of UL-DL Cfgs #1 to #6) and a UL grant/PHICH timing Ref-Cfg of theCC is set to UL-DL Cfg #0, no UL DAI signaling may be provided using aUL grant DCI format of the CC. (Instead, UL index signaling may beprovided according to a conventional scheme). In this case, the proposedA/N payload configuration and A/N ordering scheme may be equallyapplied.

(2) Method U-2: UL DAI Signaling is Provided Using a UL-DL Cfg #0Scheduling UL Grant DCI Format

According to this method, a UL DAI may be signaled instead of a UL indexwith respect to the same field in a DCI format. Although applicablecases are not restrictive, this method may be applied only to a case inwhich an SCC has UL-DL Cfg #0 and cross-CC scheduling and HD-TDD CA areconfigured (a case in which a UL grant/PHICH timing Ref-Cfg of an SCC isset to an MCC UL-DL Cfg). That is, in other cases, no UL DAI signalingis provided using a UL-DL Cfg #0 scheduling UL grant DCI format. In thiscase, a UL index may be signaled using the UL-DL Cfg #0 scheduling ULgrant DCI format as in a conventional case. Furthermore, this method maybe applied only to a CC which operates with UL-DL Cfg #0 (i.e., UL-DLCfg #0 CC) and of which a UL grant/PHICH timing Ref-Cfg is set to aUL-DL Cfg other than UL-DL Cfg #0. That is, if the UL grant/PHICH timingRef-Cfg of the UL-DL Cfg #0 CC is set to UL-DL Cfg #0, no UL DAIsignaling is provided using a UL-DL Cfg #0 scheduling UL grant DCIformat. In this case, a UL index may be signaled using the UL-DL Cfg #0scheduling UL grant DCI format as in a conventional case. A UL DAI andUL index may be signaled in the same field (e.g., 2-bit field) of a ULDCI format. In addition, this method may be applied to a CC of which aUL grant/PHICH timing Ref-Cfg is set to a UL-DL Cfg other than UL-DL Cfg#0, irrespective of UL-DL Cfgs. For example, if a CC has one of UL-DLCfgs #0 to #6 (particularly, UL-DL Cfg #0) and a UL grant/PHICH timingRef-Cfg of the CC is set to one of UL-DL Cfgs #1 to #6, no UL DAIsignaling may be provided using a UL grant DCI format of the CC.

The methods proposed above in relation to DL/UL DAI signaling may becombined according to TDD CA combination/structure, whether cross-CCscheduling is configured, A/N timing Ref-Cfg, UL grant/PHICH timingRef-Cfg, etc. For example, if an SCC has UL-DL Cfg #0 and non-cross-CCscheduling is configured, Method D-2 may be applied to DL DAI signaling,and Method U-1 may be applied to UL DAI signaling. As a result, a DL DAImay be signaled in a UL-DL Cfg #0 scheduling DL grant DCI format, and aUL DAI may not be signaled (instead of signaling a UL index) in a UL-DLCfg #0 scheduling UL grant DCI format.

Meanwhile, in CA of a plurality of CCs having different UL-DL Cfgs(irrespective of UL-DL Cfgs), an SCC may be set to a UL SF at specificSF timing when a PCC is set to a DL SF and, more particularly, the SFmay not be set to A/N timing. In this case, since there is no A/N to betransmitted at the SF timing, no UL DAI signaling may be needed by a ULgrant DCI format for scheduling UL data to be transmitted at the SFtiming. The present invention proposes to use a UL DAI field in the ULgrant DCI format for scheduling the specific SF, for another purpose asdescribed below. Here, the specific SF may be generalized to SF timingset to a UL SF but not set to A/N timing with respect to an arbitraryCC. Alternatively, (in a more generalized manner,) the proposed schememay be applied to all SF timings irrespective of A/N timing or to a fewdesignated SF timings (by using a UL DAI field, or adding a new field).

1) The UL DAI field is used to signal simultaneous transmission of aPUSCH and (periodic) CSI (e.g., PUSCH rate-matching with CSI piggyback,or no PUSCH rate-matching with CSI dropping), or simultaneoustransmission of a PUSCH and (periodic) SRS (e.g., PUSCH rate-matchingwith SRS transmission, or no PUSCH rate-matching with SRS dropping) inthe SF.

2) The UL DAI field is used to indicate a PUSCH to be transmitted (a CCfor transmitting the PUSCH) after UCI (e.g., (periodic) CSI) other thanA/N is piggybacked thereon.

FIG. 20 illustrates a UL signal transmission procedure according to anembodiment of the present invention. This embodiment shows combination[Method U-1, Method U-2], and other combinations may be performedsimilarly.

Referring to FIG. 20, a plurality of cells (e.g., cell#1 and cell#2)having different subframe configurations may be configured for a UE(S1802). Here, cell#2 may have one of UL-DL Cfgs #0 to #6 (particularly,UL-DL Cfg #0). Although cell types are not restrictive, cell#1 may be aPCell and cell#2 may be a SCell. After that, the UE may receive a UL DCIformat including a specific field (e.g., 2-bit field), for cell#2(S1804). If cross-carrier scheduling is configured, the UL DCI formatmay further include a CIF field. The UL DCI format includes DCI format0/4. After that, the UE may transmit a PUSCH signal correspondingto/indicated by the UL DCI format (S1806). Here, the PUSCH signal mayinclude HARQ-ACK information. The HARQ-ACK information may includeacknowledgement information on a PDSCH signal and/or SPS release PDCCHsignal.

According to the present invention, for UG/PHICH timing (here, PUSCH(transmission) timing), if a reference UL-DL Cfg (Ref-Cfg) applied tocell#2 is not one of UL-DL Cfgs #1 to #6 (i.e., UL-DL Cfg #0), aspecific field in a UL DCI format may indicate information used todetermine the index of a UL subframe for transmitting a PUSCH signal.That is, the specific field may indicate a UL index. In this case, aHARQ-ACK payload size of each cell may always be determined as a maximumsize. Here, the maximum size may correspond to a total number of DL SFsof each cell linked to one PCell UL SF in view of HARQ-ACK transmission(see Table 3). Specifically, HARQ-ACK payload of a cell for providing DLDAI signaling may be ordered in the order of DL DAIs and HARQ-ACKpayload of a cell for not providing DL DAI signaling may be ordered inthe order of DL SFs, or HARQ-ACK payload of all CCs may be ordered inthe order of DL SFs. On the other hand, for UG/PHICH timing (here, PUSCH(transmission) timing), if a Ref-Cfg applied to cell#2 is one of UL-DLCfgs #1 to #6, a specific field in a UL DCI format may indicate a DAIvalue (i.e., UL DAI value). The UL DAI value of a DAI field may be usedin a procedure for transmitting HARQ-ACK information (e.g., DTXdetection, HARQ-ACK payload generation, etc.).

FIG. 21 illustrates a BS 110 and a UE 120 applicable to an embodiment ofthe present invention. In a system including a relay, the BS 110 and theUE 120 may be replaced with the relay.

Referring to FIG. 21, a wireless communication system includes the BS110 and the UE 120. The BS 110 includes a processor 112, a memory 114,and a radio frequency (RF) unit 116. The processor 112 may be configuredto implement the procedures and/or methods proposed by the presentinvention. The memory 114 is connected to the processor 112 and storesvarious types of information related to operation of the processor 112.The RF unit 116 is connected to the processor 112 and transmits and/orreceives radio signals. The UE 120 includes a processor 122, a memory124, and an RF unit 126. The processor 122 may be configured toimplement the procedures and/or methods proposed by the presentinvention. The memory 124 is connected to the processor 122 and storesvarious types of information related to operation of the processor 122.The RF unit 126 is connected to the processor 122 and transmits and/orreceives radio signals. The BS 110 and/or the UE 120 may have a singleantenna or multiple antennas.

The embodiments of the present invention described above arecombinations of elements and features of the present invention. Theelements or features may be considered selective unless otherwisementioned. Each element or feature may be practiced without beingcombined with other elements or features. Further, an embodiment of thepresent invention may be constructed by combining some elements and/orfeatures. Operation orders described in embodiments of the presentinvention may be rearranged. Some configurations or features of any oneembodiment may be included in another embodiment and replaced withcorresponding configurations or features of another embodiment. It isobvious to those skilled in the art that claims that are not explicitlycited in each other in the appended claims may be presented incombination as an embodiment of the present invention or included as anew claim by a subsequent amendment after the application is filed.

In the embodiments of the present invention, a description is made,centering on a data transmission and reception relationship between a BSand a UE. In some cases, a specific operation described as performed bythe BS may be performed by an upper node of the BS. Namely, it isapparent that, in a network composed of a plurality of network nodesincluding a BS, various operations performed for communication with a UEmay be performed by the BS, or network nodes other than the BS. The term‘BS’ may be replaced with the term ‘fixed station’, ‘Node B’, ‘evolvedNode B (eNode B, eNB)’, ‘access point’, etc. The term ‘UE’ may bereplaced with the term ‘mobile station (MS)’, ‘mobile subscriber station(MSS)’, etc.

The embodiments of the present invention may be achieved by variousmeans, for example, hardware, firmware, software, or a combinationthereof. In a hardware configuration, the methods according to theembodiments of the present invention may be achieved by one or moreApplication Specific Integrated Circuits (ASICs), Digital SignalProcessors (DSPs), Digital Signal Processing Devices (DSPDs),Programmable Logic Devices (PLDs), Field Programmable Gate Arrays(FPGAs), processors, controllers, microcontrollers, microprocessors,etc.

In a firmware or software configuration, the embodiments of the presentinvention may be implemented in the form of a module, a procedure, afunction, etc. For example, software code may be stored in a memory unitand executed by a processor. The memory unit is located inside oroutside the processor and may transmit and receive data to and from theprocessor via various known means.

Those skilled in the art will appreciate that the present invention maybe carried out in other specific ways than those set forth hereinwithout departing from the spirit and essential characteristics of thepresent invention. The above embodiments are therefore to be construedin all aspects as illustrative and not restrictive. The scope of theinvention should be determined by the appended claims and their legalequivalents, not by the above description, and all changes coming withinthe meaning and equivalency range of the appended claims are intended tobe embraced therein.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a UE, a BS, or another device(e.g., relay) of a wireless communication system. Specifically, thepresent invention is applicable to a method and apparatus fortransmitting control information.

The invention claimed is:
 1. A method for transmitting control information by a user equipment (UE) in a carrier aggregation (CA)-based wireless communication system, the UE configured with a first cell set to one of uplink-downlink (UL-DL) configurations #0 to #6 and a second cell set to another of UL-DL configurations #0 to #6, the method comprising: receiving a downlink control information (DCI) having a DL DCI format comprising a downlink assignment index (DAI) field, for the second cell; and transmitting hybrid automatic repeat request (HARQ)-acknowledgement (ACK) information related to the DCI, wherein, for HARQ-ACK timing, if a reference UL-DL configuration applied to the second cell is one of UL-DL configurations #1 to #6, the DAI field is used in a procedure for transmitting the HARQ-ACK information, wherein, for HARQ-ACK timing, if a reference UL-DL configuration applied to the second cell is UL-DL configuration #0, the DAI field is not used in a procedure for transmitting the HARQ-ACK information, and wherein subframe configurations according to the UL-DL configurations #0 to #6 are given as shown in the following table: UL-DL Subframe Number Configuration 0 1 2 3 4 5 6 7 8 9 0 D S U U U D S U U U 1 D S U U D D S U U D 2 D S U D D D S U D D 3 D S U U U D D D D D 4 D S U U D D D D D D 5 D S U D D D D D D D 6 D S U U U D S U U D

where, D denotes a DL subframe, U denotes a UL subframe, and S denotes a special subframe.
 2. The method according to claim 1, wherein the first cell is set to UL-DL configuration #0, and the second cell is set to one of UL-DL configurations #1 to #6.
 3. The method according to claim 2, wherein the first cell is a primary cell (PCell), and the second cell is a secondary cell (SCell).
 4. The method according to claim 3, wherein the DL DCI format further comprises a carrier indicator field (CIF).
 5. The method according to claim 4, wherein the DL DCI format comprises DCI format 1, 1A, 1B, 1C, 1D, 2, 2A, 2B, 2C, or 2D.
 6. The method according to claim 1, wherein the HARQ-ACK information comprises at least one of acknowledgement information about a physical downlink shared channel (PDSCH) signal indicated by the DCI, or acknowledgement information about a physical downlink control channel (PDCCH) signal comprising the DCI and indicating semi-persistent scheduling (SPS) release.
 7. A user equipment (UE) used in a carrier aggregation (CA)-based wireless communication system, the UE configured with a first cell set to one of uplink-downlink (UL-DL) configurations #0 to #6 and a second cell set to another of UL-DL configurations #0 to #6, the UE comprising: a radio frequency (RF) unit; and a processor, wherein the processor is configured to: receive a downlink control information (DCI) format comprising a downlink assignment index (DAI) field, for the second cell; and transmit hybrid automatic repeat request (HARQ)-acknowledgement (ACK) information related to the DCI, wherein, for HARQ-ACK timing, if a reference UL-DL configuration applied to the second cell is one of UL-DL configurations #1 to #6, the DAI field is used in a procedure for transmitting the HARQ-ACK information, wherein, for HARQ-ACK timing, if a reference UL-DL configuration applied to the second cell is UL-DL configuration #0, the DAI field is not used in a procedure for transmitting the HARQ-ACK information, and wherein subframe configurations according to the UL-DL configurations are given as shown in the following table: UL-DL Subframe Number Configuration 0 1 2 3 4 5 6 7 8 9 0 D S U U U D S U U U 1 D S U U D D S U U D 2 D S U D D D S U D D 3 D S U U U D D D D D 4 D S U U D D D D D D 5 D S U D D D D D D D 6 D S U U U D S U U D

where, D denotes a DL subframe, U denotes a UL subframe, and S denotes a special subframe.
 8. The UE according to claim 7, wherein the first cell is set to UL-DL configuration #0, and the second cell is set to one of UL-DL configurations #1 to #6.
 9. The UE according to claim 8, wherein the first cell is a primary cell (PCell), and the second cell is a secondary cell (SCell).
 10. The UE according to claim 9, wherein the DL DCI format further comprises a carrier indicator field (CIF).
 11. The UE according to claim 10, wherein the DL DCI format comprises DCI format 1, 1A, 1B, 1C, 1D, 2, 2A, 2B, 2C, or 2D.
 12. The UE according to claim 7, wherein the HARQ-ACK information comprises at least one of acknowledgement information about a physical downlink shared channel (PDSCH) signal indicated by the DCI, or acknowledgement information about a physical downlink control channel (PDCCH) signal comprising the DCI and indicating semi-persistent scheduling (SPS) release. 